A thin film transistor array panel includes a substrate, a gate line formed on the substrate and including a gate electrode, a gate insulating layer formed on the gate line, a semiconductor formed on the gate insulating layer and including a channel of a thin film transistor, a data line formed on the semiconductor and including a source electrode and a drain electrode formed on the semiconductor and opposite to the source electrode with respect to the channel of the thin film transistor, wherein the channel of the thin film transistor covers both side surfaces of the gate electrode.